PDLUT Pre-Compensation for Nonlinear Distortion at High Baud Rates
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Solution Overview
Problem
Existing communication systems face challenges in efficiently pre-compensating non-linear distortions in data samples, particularly at high baud rates, due to the exponential increase in hardware complexity and power consumption associated with pattern-dependent lookup tables (PDLUTs) for higher modulation formats like 64QAM.
Innovation Solution
A method and system for pre-compensating non-linear distortions by generating a Pattern Dependent Lookup Table (PDLUT) through quantizing consecutive sequences of samples, computing error correction values, and storing them in a compressed form, allowing for efficient linear and non-linear distortion compensation before converting data samples into frequency and time domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Pattern Dependent Lookup Table (PDLUT) is used to compensate non-linear distortions, then distortion compensation performance is improved, but hardware complexity and power consumption increase exponentially for higher modulation formats like 64QAM
Solution Approach 1:
The patent segments the distortion compensation process into two independent stages: linear distortion compensation and non-linear distortion compensation. By dividing the PDLUT generation into separate linear and non-linear components, the hardware complexity is reduced while maintaining compensation effectiveness. The linear compensation handles frequency-selective fading, while the non-linear compensation addresses pattern-dependent distortions separately.
Solution Approach 2:
The patent extracts and removes the linear distortion component from the overall distortion compensation task. By separately compensating linear distortions first, the remaining non-linear distortions are reduced in magnitude and complexity, allowing for a smaller and more efficient PDLUT implementation for the non-linear component alone.
2Reliability
If a Pattern Dependent Lookup Table (PDLUT) is used to compensate non-linear distortions, then distortion compensation performance is improved, but power consumption increases
Solution Approach 1:
The patent segments the distortion compensation process into two independent stages: linear distortion compensation and non-linear distortion compensation. By dividing the PDLUT generation into separate linear and non-linear components, the power consumption is reduced while maintaining compensation effectiveness. The linear compensation handles frequency-selective fading, while the non-linear compensation addresses pattern-dependent distortions separately.
Solution Approach 2:
The patent extracts and removes the linear distortion component from the overall distortion compensation task. By separately compensating linear distortions first, the remaining non-linear distortions are reduced in magnitude and complexity, allowing for a smaller and more efficient PDLUT implementation for the non-linear component alone.
3Device complexity
If linear distortion compensation is provided prior to non-linear distortion compensation, then the size of the PDLUT is reduced, but the processing sequence becomes different from conventional approaches
Solution Approach 1:
The patent applies preliminary linear distortion compensation before non-linear distortion compensation. By pre-compensating linear distortions in the frequency domain, the subsequent non-linear distortion compensation operates on already-corrected signals, reducing the PDLUT size. This preliminary action simplifies the overall system complexity despite changing the conventional processing sequence.
Data Source
AI summary
Pre-compensation for linear and non-linear distortion in data symbols comprises generating a set of data symbols to be transmitted and converting the set into a set of frequency-domain samples, which are then pre-processed. Linear distortion compensation is provided, prior to compensating for non-linear distortions, to the pre-processed set of frequency-domain samples. The linear distortion compensated set of frequency-domain samples is converted into a linear distortion compensated set of time domain samples. Non-linear distortion compensation is provided to the linear distortion compensated set of time domain samples. A Pattern Dependent Lookup Table (PDLUT) is generated by receiving consecutive sequences of samples included in a set of time domain samples, quantizing the consecutive sequences of samples into integer-valued consecutive sequences of samples, computing error correction values corresponding to the integer-valued consecutive sequences of samples, and storing the indexes of integer-valued consecutive sequences of samples and the corresponding error correction values in the PDLUT.